A biopsy needle is employed by a physician to remove from a patient a small piece of tissue permitting the tissue to be subsequently examined pathologically in order to determine the condition of the tissue, particularly with respect to the existence of undesired cells.
The excision of tissue should be achieved with minimum injury to the balance of the tissue. Attempts have been made to employ a flexible, reciprocating blade within a support or housing which penetrates the portion of the body being examined with a portion of the tissue penetrating the interior of the body prior to advancing the blade or stylus whose cutting edge severs the tissue internally of the body and retains it during removal or retrieval of the needle. U.S. Patents representative of such procedure and instruments employed therein are U.S. Pat. Nos. 1,564,356: 2,131,780: 3,007,471: 3,407,815 and 4,651,752.
U.S. Pat. No. 4,651,752 to Fuerst, issuing Mar. 24, 1987 is directed to such a biopsy needle in an attempt to obtain a specimen which fills the entire volume of a recess within the needle sheath or hollow tubular body and which effectively cuts the tissue clearly and retains it securely for safe retrieval. In attempting to reach that end, the cutting action provided is essentially clean, occurring at the base of the incursion with little or no tearing of the tissue. While the biopsy needle of Fuerst is an advancement in the art, the cross-sectional configuration of the tubular needle body is circular, a wall of the circular cross-section tubular body is flattened to one side and a thin, rectangular flexible blade is slidably mounted on the body, to close off an opening within the body itself over the length of the body. Further the blade terminates in a triangular shape tip in an attempt to close off the oblique cutting edge at the distal end of the needle body, with edges of the tip received within opposed grooves within the body running the length of the body to the sides of opening toward the sharpened point of that body. The biopsy needle of Fuerst has several deficiencies. First of all, the needle body is open at its side opposite that of the distal end tip, and the sliding blade makes contact between the blade and the patient tissue over its complete length. Secondly, with the blade retracted, transfer of fluids may occur between the bore of the needle and the tissue. Additionally, the planar configuration of the needle body cutting edge at the distal end is curved or arcuate over the complete extent of the same, inherently preventing the cutting blade from closing off the biopsy needle body at its distal end and preventing the cutting blade from neatly and cleanly severing the tissue encased by the needle and completely closing off the bore of the biopsy needle during tissue severence.
It is therefore a primary object of the present invention to provide an improved biopsy needle which is relatively small in size, simple in construction, which employs a hollow tubular biopsy needle body whose transverse section inherently provides a greater cross-section of area for amassing severed tissue during operation of the reciprocal guillotine blade, wherein the sharp cutting edge of the needle body distal end is at the inside surface of the tubular body, wherein the reciprocating blade is effectively guided during its complete extent of movement from retracted to extended, cutting position and vice versa in lateral straight edge sealed contact with the interior of the hollow needle body, wherein the blade is always within the bore of the needle to maximize safety to the physician using the instrument, wherein there are no moving parts on the outer surface portion of the needle body in contact with the tissue beneath the patient's skin, and wherein the shape of the tubular needle body facilitates orientation of the needle in the tissue relative to the location of the blade internally and its reciprocation path, and which insures severence of a full section of biopsied tissue at the very tip of the needle.